Fig. 4

Histopathological changes in airway inflammation and airspace in different airway models by PM. (A) Hematoxylin–eosin (H&E) staining of right lung sections from COPD-C and COPD-A mice. Bright-field microscopy images show inflammatory responses around airways, (B) Inflammation grades for peribronchial and perivascular inflammation from H&E staining, (C) Lung parenchyma stained with H&E showing airspace enlargement, and (D) Airspace size evaluated by the mean lineal intercept. COPD, chronic obstructive pulmonary disease; PM, particulate matter. *: p < 0.05, **: p < 0.01, ***: p < 0.001 and ****: p < 0.0001, and ns: non-significant